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. Author manuscript; available in PMC: 2007 Mar 29.

Published in final edited form as: J Neurochem. 2004 Aug;90(4):970–978. doi: 10.1111/j.1471-4159.2004.02566.x

Table 3.

Kinetic parameters for DOPA binding to human tyrosine hydroxylase isoforms

	Unphosphorylated enzyme			Phosphorylated enzyme
Isoform	k_on^a (mM⁻¹ min⁻¹)	k_off^b (min⁻¹)	K_d^c (μM)	k_on^a (mM⁻¹ min⁻¹)	k_off^b (min⁻¹)	K_d^c (μM)
hTyrH₁	18.6 ± 0.6	0.082 ± 0.001	4.45 ± 0.16	61.2 ± 2.4	0.453 ± 0.012	7.41 ± 0.36
hTyrH₂	17.4 ± 1.2	0.078 ± 0.001	4.52 ± 0.32	51.6 ± 3.0	0.334 ± 0.005	6.48 ± 0.40
hTyrH₃	10.8 ± 0.6	0.034 ± 0.001	3.17 ± 0.21	40.2 ± 1.8	0.235 ± 0.015	5.87 ± 0.47
hTyrH₄	14.4 ± 1.2	0.060 ± 0.001	4.21 ± 0.36	35.4 ± 1.2	0.142 ± 0.002	4.02 ± 0.16
Rat TyrH^d	39.0 ± 3.6	0.102 ± 0.006	2.70 ± 0.29	66.0 ± 4.8	2.76 ± 0.54	41.7 ± 13.9

^a

Conditions: 10% glycerol, 100 mM KCl, 50 mM HEPES, pH 7, 10°C.

^b

Conditions: 1 mM DHN, 60 μm DOPA, 10% glycerol, 100 mM KCl, 0.2 mM DTPA, 50 mM HEPES, pH 7, 10°C.

^c

Calculated from the corresponding k_on and k_off values.

^d

From reference (McCulloch et al. 2001), determined at 15°C.